P38.14: Corpus callosum: comparision between bidimensional and volumetric ultrasound

17th World Congress on Ultrasound in Obstetrics and Gynecology

for mild unilateral ventriculomegaly (1.14 cm). A rescan was done at 22 weeks, 26 weeks, 28 weeks and 30 weeks, respectively. It only revealed mild unilateral ventriculomegaly. We arranged MRI at 22 weeks’ gestation and 32 weeks’ gestation, respectively. There was just multicystic encephalomalacia at 32 weeks’ gestation. Finally, she decided to termination of the pregnancy after feticide. Discussion: Prenatal sonography are valuable tools for the early finding of intracranial lesions and need fetal MRI to confirm the brain lesion. We suggest the fetal MRI optimal time for brain lesion may be at 30–34 weeks.

P38.12 Two cases of arachnoid cyst of prenatal diagnosis S. A. Lee, J. K. Park, S. I. Kim, J. K. Shin, J. H. Lee, W. Y. Paik Gyeongsang National University, Republic of Korea Intracranial arachnoid cysts are collections of clear fluid within the arachnoid membrane because of nondisjunction or duplication of the structure. They are rare, representing only 1% of intracranial masses in newborns. Etiologically, they are thought to be due to maldevelopment of the arachnoid or secondary to trauma or infection. The arachnoid cyst by ultrasonogram shows characteristic well capsulated homogeneous hypoechoic cyst. Many arachnoid cysts remain asymptomatic, however, and become symptomatic later in life to cyst growth - resulting in a compression, displacement and irritation of the surrounding structures. So, early diagnosis and treatment of these cysts are important. We present two cases of arachnoid cysts diagnosed in utero by ultrasonogram. In one case, postnatal MRI was checked and confirmed an arachnoid cyst with choroid plexus cyst. In another case, postnatal brain USG was checked and diagnosed an arachnoid cyst. Both children are asymptomatic, and presenting normal development until now.

P38.13 Fetal optic chiasm measurements: reference range at 22–36 weeks of gestation J. P. Bault1 , L. J. Salomon2 Centre d’Echographies Ambroise Par´e, France, 2 CHI Poissy Saint-Germain, France 1

Introduction: Development of volume ultrasound has made it possible to visualize the optic chiasm in the second and third trimesters of pregnancy. We aimed to build new reference ranges for fetal optic chiasma measurements at 22–36 weeks. Materials and methods: The width of the posterior branches of the fetal optic chiasm were measured at 22 to 36 weeks of gestation during routine screening examination by a single operator. Measurements were based on volume acquisitions of the fetal optic chiasm. Exclusion criteria were a known abnormal karyotype or congenital malformation and multiple pregnancies. No data were excluded on the basis of abnormal biometry. We used a polynomial regression approach (mean and standard deviation model) to compute new reference charts for fetal optic chiasm measurement. Results: 58 fetuses were included. The size of the branches of the optic chiasm with GA was best described with a linear regression (R =0.99). There was no evidence of increased variability over GA (constant standard deviation). New charts and equations for Z-scores calculations are reported at between 22 and 36 weeks. Conclusion: We present new reference charts and equations for measurements of the fetal optic chiasm. When an anterior brain abnormality such as septal agenesis is suspected, such charts may be useful to assess the development of the optic chiasm.

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Poster abstracts

P38.14 Corpus callosum: comparision between bidimensional and volumetric ultrasound M. Signorelli, L. Franceschetti, F. Taddei, T. Frusca, N. Palai, C. Groli University of Brescia, Italy Objectives: Comparision between bidimensional (2D) imaging (transabdominal- TA or transvaginal -TV) and three-dimensional (3D) technique in the identification of corpus callosum (CC) and in the definition of its integrity. Methods: 200 single normal pregnancies were evaluated at 20–22 weeks. Using both bidimensional and volumetric techniques, detailed ultrasound evaluation of the fetal anatomy was investigated and the exam lasted up to 60 minutes. The characterization of the corpus callosum imaging was evaluated considering definition of borders and identification of rostrum, genu, body and splenium. Results: With the 2D technique the CC was documented in all cases: it was identified at the beginning of the exam in 53% of cases (47% TA, 6% TV), at 30 minutes in 27% (TA), and at 60 minutes in 20% (18% TA, 2% TV). With the 3D technique the CC was documented in 92% of cases: it was identified at the beginning of the exam in 87% of cases, and at 30 and 60 minutes in 5% of fetuses. The 2D imaging of the CC was well-defined in all cases, and its 4 parts were visualized. The 3D CC imaging was considered clear in 78% of cases, but in 14% of fetuses it was impossible to define its limits and components. Conclusions: The 3D approach leads to an immediate acquisition of CC imaging in the majority of cases; on the other hand, the 2D technique requires a very long examination time in 5% of cases. In our series, the CC was always identified using the 2D technique with an extension of examination time, in order to achieve different fetal positions, whereas using 3D technique this acquisition was not feasible in all cases. Definition of CC imaging is better with 2D ultrasound, whereas 3D technique offers good quality imaging only in optimum examination situations. The advantage of the rapid acquisition offered by 3D approach could be useful in routine ultrasound examination, in which there is a short examination time even though in these cases, CC visualization is non demanded.

P39: FETAL ECHOCARDIOGRAPHY AND CHD II P39.01 Fetal cardiac tumor: prenatal diagnosis and postnatal outcome K. Nam, H. Hwang, D. Kwak, Y. Park, Y. Kim Yonsei University Medical Center, Department of Obstetrics and Gynecology, Republic of Korea Objectives: The objective of this study was to evaluate the sonographic appearance of suspected fetal cardiac tumor and their evolution until delivery and in the postnatal period, and to document the associated problems including tuberous sclerosis. Materials and method: We retrospectively reviewed the medical records of all cases born in Yonsei University Medical Center, Seoul, Korea, between 1996 and 2006, and diagnosed as fetal cardiac tumor prenatally. Results: Ten cases were found in all medical records. The mean age of the mothers on delivery was 30.2 ± 2.44 years and the mean gestational age on diagnosis was 30.6 ± 5.44 weeks. The cardiac tumors were single in four cases and multiple in the other six cases. The size varies from 7 to 34 mm. Most of the tumors were located in right ventricle (RV, n = 9), left ventricle (LV, n = 6), but they were also located in interventricular septum (IVS, n = 3) and right atrium (RA, n = 1). In one case, fetal arrhythmia, which was normalized in two days after birth was found and in another case, mild intracardiac flow obstruction was noted. The duration of postnatal follow-up

Ultrasound in Obstetrics & Gynecology 2007; 30: 547–653